U.S. patent number 10,737,658 [Application Number 15/810,437] was granted by the patent office on 2020-08-11 for hybrid method and apparatus for detecting a vehicle/pedestrian impact.
This patent grant is currently assigned to TRW AUTOMOTIVE U.S. LLC. The grantee listed for this patent is TRW AUTOMOTIVE U.S. LLC. Invention is credited to Chek-Peng Foo, Ying-chang Lee, Huahn-Fern Yeh.
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United States Patent |
10,737,658 |
Foo , et al. |
August 11, 2020 |
Hybrid method and apparatus for detecting a vehicle/pedestrian
impact
Abstract
An apparatus detects a vehicle/pedestrian impact event by
sensing impact events near a forward location of a vehicle using
both acceleration sensors and pressure sensors and providing
associated signals indicative thereof, determining metric values
for each of the sensor signals, and determining if a
vehicle/pedestrian impact has occurred in response to the
determined metric values.
Inventors: |
Foo; Chek-Peng (Ann Arbor,
MI), Yeh; Huahn-Fern (Novi, MI), Lee; Ying-chang
(Middleton, MI) |
Applicant: |
Name |
City |
State |
Country |
Type |
TRW AUTOMOTIVE U.S. LLC |
Livonia |
MI |
US |
|
|
Assignee: |
TRW AUTOMOTIVE U.S. LLC
(Livonia, MI)
|
Family
ID: |
49624185 |
Appl.
No.: |
15/810,437 |
Filed: |
November 13, 2017 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20180065592 A1 |
Mar 8, 2018 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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14401877 |
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9855915 |
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PCT/US2012/038982 |
May 22, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60R
21/00 (20130101); B60R 21/36 (20130101); B60R
21/34 (20130101); B60R 21/0136 (20130101); B60R
21/38 (20130101); B60R 21/0132 (20130101); B60R
19/483 (20130101) |
Current International
Class: |
B60R
21/38 (20110101); B60R 21/00 (20060101); B60R
21/34 (20110101); B60R 21/36 (20110101); B60R
21/0132 (20060101); B60R 21/0136 (20060101); B60R
19/48 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102008008746 |
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Aug 2008 |
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DE |
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102008008746 |
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Sep 2009 |
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DE |
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10002110 |
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Jul 2011 |
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DE |
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102012101296 |
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Feb 2012 |
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DE |
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2009196463 |
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Sep 2009 |
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JP |
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03082639 |
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Oct 2003 |
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WO |
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Other References
PCT/US2012/038982 International Search Report & Written Opinion
Completed Jul. 18, 2012. cited by applicant .
PCTUS13/26589 International Search Report & Written Opinion,
Completed Apr. 3, 2013. cited by applicant.
|
Primary Examiner: Kong; Sze-Hon
Attorney, Agent or Firm: Tarolli, Sundheim, Covell &
Tummino LLP
Parent Case Text
RELATED APPLICATION
This application is a divisional of U.S. patent application Ser.
No. 14/401,877, filed Apr. 9, 2015, and which is a U.S. National
Stage Application filed under 35 U.S.C. .sctn. 371 of
PCT/US2012/038982, filed on May 22, 2012. The disclosures of these
applications are hereby incorporated by reference in their
entireties.
Claims
Having described the invention, the following is claimed:
1. An apparatus for detecting a vehicle/pedestrian impact
comprising: at least one acceleration sensor mounted near a forward
location of a vehicle for providing an associated acceleration
signal indicative of an impact event; at least one pressure sensor
mounted near the forward location of the vehicle for providing a
first pressure signal associated with a left side of the vehicle
and a second pressure signal associated with a right side of the
vehicle, the first and second pressure signals being indicative of
an impact event; and a controller configured to determine if a
vehicle/pedestrian impact event has occurred in response to the
acceleration signal and the first and second pressure signals,
wherein the controller is configured to determine if a
vehicle/pedestrian impact event has occurred by determining an
impact energy value from the acceleration signal, comparing a first
determined moving average value of the first pressure signal as a
function of the impact energy value against a first associated
threshold value, and comparing a second determined moving average
value of the second pressure signal as a function of the impact
energy value against a second associated threshold, wherein the
controller is further configured to provide an actuation control
signal in response to determining the impact event occurred.
2. The apparatus of claim 1 wherein the first and second associated
thresholds are identical.
3. The apparatus of claim 1 where the first and second associated
threshold values are selected in response to monitored vehicle
speed.
4. The apparatus of claim 1 further including an actuatable
vehicle/pedestrian impact mitigation device attached to the vehicle
and being responsive to the actuation control signal.
5. The apparatus of claim 1 wherein the impact energy value is
determined from frequency components of the acceleration signal
over a predetermined frequency range.
6. The apparatus of claim 1 wherein the at least one acceleration
sensor includes two spaced apart sensors mounted to a forward
structure of the vehicle.
7. The apparatus of claim 1 wherein the at least one acceleration
sensor includes three spaced apart sensors mounted to a forward
structure of the vehicle.
8. The apparatus of claim 1 wherein the at least one pressure
sensor includes a single channel pressure sensor and a single
pressure tube connected to the single channel pressure sensor, the
pressure tube having a closed distal end and is mounted to a
forward structure of the vehicle.
9. The apparatus of claim 1 wherein the at least one acceleration
sensor comprises a first acceleration sensor mounted at a center
forward location of the vehicle, a second acceleration sensor
mounted at a leftward forward location of the vehicle, and a third
acceleration sensor mounted at a rightward forward location of the
vehicle.
10. The apparatus of claim 1 wherein the at least one pressure
sensor is a multi channel pressure sensor having a plurality of
pressure hoses connected thereto, the plurality of pressure hoses
being mounted near the forward location of the vehicle for
providing an associated pressure signal indicative of an impact
event.
Description
TECHNICAL FIELD
The present invention relates to a protection system and, more
particularly, to a hybrid method and apparatus for detecting a
vehicle/pedestrian impact using both acceleration and pressure
detection.
BACKGROUND OF THE INVENTION
Vehicle occupant protection devices for helping to protect a
vehicle occupant during a vehicle event such as a crash, roll-over,
etc., are known. To detect such a vehicle event, one or more event
sensors are mounted to the vehicle and provide signals indicative
of sensed vehicle event conditions for which actuation of the
protection device may be desired. The event sensors are connected
to an electronic controller that evaluates the event sensor signals
using appropriate event metrics to monitor and determine if a
particular event is occurring, e.g., a vehicle crash condition.
Upon determining the occurrence of a particular type of vehicle
event by the electronic controller, the vehicle occupant protection
devices, e.g., air bags, inflatable side curtains, etc., are
actuated.
Pedestrian protection systems have been proposed to aid in reducing
pedestrian injury when the pedestrian is struck by a moving vehicle
(a "vehicle/pedestrian impact"). Some proposed pedestrian
protection systems include a sensor mounted in the vehicle bumper.
If the sensor detects an impact with a pedestrian, an actuatable
device is actuated to mitigate the impact effect. Such actuatable
devices include, for example, actuators to raise the trailing end
of the hood upward. Actuatable forward mounted air bags have also
been proposed to mitigate vehicle/pedestrian impact effects.
SUMMARY OF THE INVENTION
In accordance with the present invention, a method and apparatus
are provided for determining vehicle/pedestrian impact metric
values using forward mounted accelerometers and pressure sensors
and analyzing the values to determine if a vehicle/pedestrian
impact is occurring.
In accordance with one example embodiment of the present invention,
an apparatus is provided for detecting a vehicle/pedestrian impact
comprising a least one acceleration sensor mounted near a forward
location of a vehicle for providing an associated acceleration
signal indicative of an impact event. At least one pressure sensor
is mounted near the forward location of the vehicle for providing
an associated pressure signal indicative of an impact event. A
controller determines if a vehicle/pedestrian impact event has
occurred in response to the acceleration signal and the pressure
signal.
In accordance with another example embodiment of the present
invention, an apparatus is provided for detecting a
vehicle/pedestrian impact comprising a least one acceleration
sensor mounted near a forward location of a vehicle for providing
an associated acceleration signal indicative of an impact event. At
least one multi-channel pressure sensor having a plurality of
pressure hoses is connected thereto, the plurality of pressure
hoses being mounted at associated different locations along a
forward structure of the vehicle, each pressure hose providing an
associated pressure indication to the multi-channel pressure sensor
of an impact event, the multi-channel pressure sensor providing an
associated electrical signal indicative of an impact event
encountered by any of the pressure hoses. A controller is provided
for determining if a vehicle/pedestrian impact event has occurred
in response to the acceleration signal and the associated
electrical signal from the multi-channel pressure sensor and for
providing an actuation control signal in response thereto.
In accordance with another example embodiment of the present
invention, an apparatus is provided for detecting a
vehicle/pedestrian impact comprising a plurality of acceleration
sensors each mounted near a forward location of a vehicle for
providing associated acceleration signals indicative of a
vehicle/pedestrian impact event. At least one pressure sensor is
mounted near the forward location of the vehicle for providing an
associated pressure signal indicative of an impact event, and a
controller is provided for determining if a vehicle/pedestrian
impact event has occurred in response to the acceleration signals
and the pressure signal and for providing an actuation control
signal in response thereto.
In accordance with another example embodiment of the present
invention, a method is provided for detecting a vehicle/pedestrian
impact comprising the steps of sensing impact events near a forward
location of a vehicle using both acceleration sensors and pressure
sensors and providing associated signals indicative thereof,
determining vehicle/pedestrian impact metric values for each of the
sensor signals and determining if a vehicle/pedestrian impact has
occurred in response to the determined vehicle/pedestrian impact
metric values.
DETAILED DESCRIPTION OF THE DRAWINGS
The foregoing and other features and advantages of the present
invention will become apparent to one skilled in the art upon
consideration of the following description of exemplary embodiments
of the invention and the accompanying drawings, in which:
FIG. 1 illustrates a vehicle/pedestrian impact detection device in
accordance with one exemplary embodiment of the present
invention;
FIG. 2 is a functional block diagram showing a portion of the
control logic used by the electronic control unit of FIG. 1 for
detection of a vehicle/pedestrian impact in accordance with an
exemplary embodiment of the present invention;
FIG. 3 illustrates a vehicle/pedestrian impact detection device in
accordance with another exemplary embodiment of the present
invention;
FIG. 4 is a functional block diagram showing a portion of the
control logic used by the electronic control unit of FIG. 3 for
detection of a vehicle/pedestrian impact in accordance with an
exemplary embodiment of the present invention;
FIGS. 5-8 are block diagrams showing portions of discrimination
control logic followed by the electronic control unit of FIG. 3
during different type of vehicle/pedestrian impact events in
accordance with an exemplary embodiment of the present
invention;
FIG. 9 is a block diagram showing another portion of the
discrimination control logic of the electronic controller of FIG.
3; and
FIG. 10 illustrates a vehicle/pedestrian impact detection device in
accordance with yet another exemplary embodiment of the present
invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
Referring to FIG. 1, a detection apparatus 50, in accordance with
an exemplary embodiment of the present invention, is provided for
detecting a vehicle/pedestrian impact event. The detection
apparatus 50 includes a plurality of sensors 54 mounted at the
front portion of a vehicle 52. In accordance with one example
embodiment of the present invention, shown specifically in FIG. 1,
the sensors 54 include a plurality of acceleration sensors 62, 64
mounted in a spaced apart fashion to a forward cross-member 68
(e.g., a bumper cross-beam) of the vehicle 52 so as to be
positioned at a left front location and a right front location,
respectively, of the vehicle 52. A sensing architecture that uses
acceleration sensors mounted near the front of a vehicle for
vehicle/pedestrian impact detection can be found in co-pending
patent application U.S. Ser. No. 12/778,505 filed May 12, 2010 to
Foo et al. (U.S. Patent Application Publication No. 2011/0282553
published Nov. 17, 2011) which is hereby fully incorporated herein
by reference.
The acceleration sensors 62, 64, in accordance with an example
embodiment of the present invention, are multi-axis acceleration
sensors ("MAS"), although single-axis acceleration sensors ("SAS")
could alternatively be used. The acceleration sensors 62, 64 each
provide an associated electrical signal having electrical
characteristics (e.g., frequency, amplitude, etc.) indicative of a
sensed acceleration as a result of an impact event between the
vehicle 52 and an object such as a pedestrian (not shown). This
type of impact event is referred to herein as a "vehicle/pedestrian
impact event."
The sensors 54 further include a pressure sensor assembly or
arrangement 70. The pressure sensor assembly 70 includes a pressure
tube or hose 72 secured to the front of the forward cross-member
68. The front bumper structure of the vehicle 52 includes energy
absorbing foam 74 that contacts a forward facing portion of the
pressure hose 72. The pressure sensor assembly 70 further includes
a pressure sensor 76 operatively connected to and in operative
fluid communication with the pressure hose 72. The pressure hose 72
is sealed at the distal end opposite the end connected to the
pressure sensor 76. The pressure hose 72 is an open tube (i.e.,
hollow) filled with a gas, such as air but is, in effect, a closed
chamber being sealed off at the distal end and in fluid
communication with the pressure sensor 76. If the vehicle bumper is
pushed in, as may occur when a pedestrian is hit by the vehicle 52,
the energy absorbing foam 74 will push against the pressure hose
thereby increasing the pressure inside of the pressure hose 72. The
pressure against the hose during a vehicle/pedestrian impact event
squeezes the hose and decreases the hose volume that, in turn,
increases air pressure within the closed hose. The increase in
pressure within the pressure hose 72 will be sensed by the pressure
sensor 76. The pressure sensor 76 provides an electrical output
signal having an electrical characteristic indicative of sensed
pressure, i.e., the pressure within the hose 72. Since this
arrangement has a single pressure sensor, it is referred to herein
as a single channel pressure ("SCP") sensor.
Each of the event sensors 62, 64, 76 is electrically connected to
an electronic control unit ("ECU") 80 for monitoring and processing
the accelerometer signals from sensors 62, 64 and the pressure
signal from sensor 76. The ECU 80 may be a microcontroller, a
microprocessor, discrete circuitry, and/or an application specific
integrated circuit ("ASIC") designed to function in accordance with
the present invention. The ECU 80 may be located within the cabin
of the vehicle 52 or other area of the vehicle. The ECU 80 is
connected to the accelerometers 62, 64 and pressure sensor 76 via a
direct electrical connection, via a communication bus, via any
other wiring arrangement, or even wirelessly. The output signal
from the acceleration sensor 62 is referred to herein as PPS_MAS
Left. The output signal from the acceleration sensor 64 is referred
to herein as PPS_MAS Right. The output signal from the pressure
sensor 76 is referred to herein as PPS_SCP.
The vehicle 52 may also include an electronic stability control
("ESC") system 82 that provides the ECU 80 with electrical signals
indicative of certain other sensed vehicle operating conditions
such as a vehicle speed signal. The sensor signals from the ESC
system 82 can either be directly connected to the ECU 80, or sensor
signals from the ECS can be communicated to the ECU 80 via the
vehicle's controller area network ("CAN") Bus 83. Alternatively, a
separate vehicle speed sensor could be provided for monitoring
vehicle speed and sending a vehicle speed signal directly to the
ECU 80.
The ECU 80 is further electrically connected to an actuatable
vehicle/pedestrian impact mitigation device 84. The actuatable
impact mitigation device 84 includes, in accordance with one
example embodiment of the present invention, actuators 86, 88
located at the trailing end of the vehicle hood 90 so that, when
actuated by the ECU 80, the actuators 86, 88 lift the trailing end
of the hood 90 upward thereby allowing the slanted hood to mitigate
pedestrian injury during a vehicle/pedestrian impact event. The
actuators 86, 88 can be actuatable via, for example, pyrotechnics.
Other means for actuating the actuators 86, 88 are also
contemplated. Also, rather than hood actuators for
vehicle/pedestrian impact mitigation, other actuatable devices
could be used such as forward mounted air bags.
Referring to FIG. 2, the control logic performed by the ECU 80, in
accordance with an example embodiment of the present invention, is
shown. This control logic determines if there is a
vehicle/pedestrian impact event occurring by combining information
from the acceleration sensors 62, 64 and the pressure sensor 76,
i.e., a determination based on a hybrid sensor arrangement
combining acceleration and pressure. The vehicle speed signal from
the ESC system 82 is also monitored by the ECU 80. One of a
plurality of sets of threshold values is selected in response to
the monitored vehicle speed value as part of the vehicle/pedestrian
impact determination. In accordance with one example embodiment of
the present invention, the vehicle speed being between a minimum
vehicle speed value 102 and a maximum speed value 104 is classified
by velocity range classifier logic ("VRCL") 116 of the ECU 80 as
falling within, for example, one of three specific speed ranges.
The speed or velocity values that define a particular speed range
may overlap with adjacent speed range(s). Each speed range has
associated therewith, a set of threshold values that are used in
the control process performed by the ECU 80 for deciding whether to
actuate the actuatable impact mitigation device 84, i.e.,
determining if a vehicle/pedestrian impact event is occurring. If
the monitored vehicle speed is less than a minimum vehicle speed
102, for example 20 KPH, or if the monitored vehicle speed is
greater than the maximum vehicle speed 104, for example 50 KPH, the
ECU 80 will not permit actuation of the actuatable pedestrian
impact mitigation device 84 regardless of the values of the signal
outputs from the sensors 62, 64, and 76. Therefore, it should be
appreciated that each of the speed ranges relevant for possible
actuation of the actuatable devices all fall between the minimum
102 and maximum 104 vehicle speed values.
As mentioned, the sensed vehicle speed between the minimum vehicle
speed 102 and the maximum vehicle speed 104 is divided or
classified into one of the predetermined number of discrete speed
ranges, e.g., a low-velocity range or set 110, a mid-velocity range
or set 112, or a high velocity range or set 114. The mid-velocity
range 112 values and the low-velocity range 110 values can have
overlapping velocity values, and the mid-velocity range 112 values
and the high-velocity range 114 values can have overlapping
velocity values. The classification of the monitored vehicle
velocity value into one of the velocity ranges by the velocity
range classifier logic 116 establishes a threshold value set used
in later logic processing described below. If the vehicle speed
falls in an overlap velocity range area, threshold sets associated
with each of the velocity ranges are used by the ECU 80 in its
discrimination determination process with the results of the
determinations being logically OR'ed. The threshold value set(s)
selected in response to the velocity range classifier logic 116 is
used in a discrimination determination functions (or discrimination
logic) 120 and 122 of the ECU 80.
The ECU 80 determines acceleration metric values from the outputs
PPS_MAS Left and PPS_MAS Right of the acceleration sensors 62, 64,
respectively, using metric computation functions 130, 132,
respectively. Specifically, the output signal from each of the
accelerometers 62, 64 is monitored by the metric computation
functions 130, 132, respectively, and associated displacement
values are determined. The displacement values are determined using
a moving average value of the acceleration signals PPS_MAS Left and
PPS_MAS Right over a time widow. The moving average value of the
acceleration from the PPS_MAS Left sensor 62 over the time window
is referred to as A_MA_Left and is determined in left
discrimination function 130. The moving average value of the
acceleration from the PPS_MAS Right sensor 64 over the time window
is referred to as A_MA_Right and is determined in discrimination
function 132. Displacement values (double integral of acceleration)
are then determined using the A_MA_Left and A_MA_Right values
within the discrimination functions 130, 132, respectively. In
addition to determining the displacement values based on each of
the left and right acceleration signals, an impact energy value is
also determined based upon each of the acceleration sensor signals
from sensors 62, 64. The determined impact energy values are based
on the associated acceleration sensor signals within a
predetermined frequency range. The impact energy values are
referred to as HPF_Left and HPF_Right. The discrimination logic
functions 120 and 122 compare each determined displacement metric
value A_MA_Left and A_MA_Right as a function of the determined
impact energy HPF_Left and HPF_Right, respectively, against the
threshold sets established by the velocity range classifier logic
116. The output of each of the discrimination logic functions 120
and 122 is electrically connected to one input of logic AND
functions 140, 142, respectively.
In the discrimination logic functions 120, 122, each of the two
determined displacement metric values as a function of impact
energy is compared against a threshold set (two threshold sets if
the vehicle speed falls within an overlap portion of the speed
ranges) selected from the velocity range classifier logic 116. If
the vehicle velocity value does fall within overlapped speed
ranges, the comparisons of displacement as a function of impact
energy against the threshold sets from both speed ranges are
logically OR'ed. The discrimination logic functions 120, 122
determine if a vehicle/pedestrian impact event, as sensed by the
associated acceleration sensor 62, 64, respectively, is above a
predetermined value
In another portion of the control logic shown in FIG. 2, the output
signal PPS_SCP from the pressure sensor 76 is processed by
associated metric computation function 144. The value determined by
the metric computation functions 144 is a moving average value of
the pressure over a time window and is referred to herein as
P_MA_S. The determined pressure moving average P_MA_S is compared
against an associated fixed threshold in a safing logic function
146 to determine if a vehicle/pedestrian impact event, as sensed by
the pressure sensor 76, is above a predetermined value.
The output of the resultant comparison performed in the safing
logic function 146 is connected to the other (the second) input of
each of the logical AND functions 140, 142. The output of the logic
AND function 140 represents a system response 148 for left side
impacts and the output of the logic AND function 142 represents a
system response 150 for right side impacts. The two system
responses 148 and 150 are logically OR'ed in logic OR function 152.
The output of the logic OR function 152 is used as the actuator
control signal for the actuators 86, 88. In effect, the pressure
sensor 76 is used as a safing function that is AND'ed with the
discrimination determinations based on the left and right sensed
accelerations. If certain displacement metric values (left or
right) as a function of their associated determined impact energy
value is greater than a predetermined threshold and a pressure
metric value is greater than a predetermined amount, the actuators
86, 88 are actuated.
Referring to FIG. 3, a second sensor system architecture having
sensors 70' is shown in accordance with another example embodiment
of the present invention. In accordance with this example
embodiment, acceleration sensors 62, 64 are mounted to the forward
cross-member 68 as previous described. In this embodiment, a
multi-channel pressure sensor 76' ("PPS_MCP") is connected to two
separate pressure hoses 160 left and 162 right. The pressure sensor
76' is a dual channel pressure sensor. In this way, the pressure
sensor 76' can sense pressures from impact events on both the left
and right sides of the vehicle and can provide both a left pressure
signal (PPS_MCP Left) and a right pressure signal (PPS_MCP Right)
to the ECU 80' for processing.
Referring to FIG. 4, the control logic followed by the ECU 80' is
depicted for the sensor architecture of FIG. 3. In this control
arrangement, a pressure left safing determination is logically
AND'ed with the left acceleration determination in AND function
164. Similarly a pressure right safing determination is logically
AND'ed with the right acceleration determination in AND function
166. In effect, instead of a safing function using one pressure
sensor, the arrangement of FIG. 4 provides separate left and right
pressure safing determinations with the left pressure safing
determination AND'ed with the left acceleration discrimination
determination and the right pressure safing determination AND'ed
with the right acceleration discrimination determination.
FIGS. 5-8 depict various example discrimination conditions for the
vehicle sensor architecture shown in FIG. 3 using the control logic
shown in FIG. 4. In particular, FIG. 5 depicts the affect of a
severe rough-road misuse condition (a condition for which actuation
of the actuators 86, 88 is not desired) when the vehicle velocity
falls within one vehicle velocity band. As can be seen, since
neither the left or right pressure safing values cross their
associated threshold, no actuation of the actuators 86, 88 would
occur. FIG. 6 depicts the affect of a left impact misuse condition
(a condition for which actuation of the actuators 86, 88 is not
desired) when the vehicle velocity falls within one vehicle
velocity band. As can be seen, although the PPS_MCP Left exceeds
its associated threshold, the left acceleration signal PPS_MAS does
not exceed its threshold. Since neither the right pressure signal
nor right acceleration signal exceed their associated thresholds,
no actuation occurs of the actuators 86, 88. FIG. 7 depicts a no
fire left vehicle/pedestrian impact event in which the left
pressure sensor PPS_MCP Left exceeds its associated threshold but
the left acceleration sensor PPS_MAS does not exceed its associated
threshold. FIG. 8 depicts a must fire left vehicle/pedestrian
impact event. As can be seen, since both the PPS_MAS Left
acceleration exceeds its associated threshold and the left pressure
PPS_MCP Left exceeds its associated threshold, the actuators 86, 88
would be actuated.
Referring to FIG. 9, the determination metric calculations for the
sensor architecture shown in FIG. 3 and the control logic shown in
FIG. 4 will be appreciated. Each of the acceleration sensors 62, 64
output an electrical signal having electrical characteristics such
as frequency and amplitude indicative of a vehicle/pedestrian
impact event resulting in acceleration of at least that portion of
the vehicle where the sensors are mounted. Each sensor 62, 64 has
its own associated metric calculation to determine displacement
values over a time window and to determine an impact energy value
based on impact energy over a particular frequency range. The
controller 80' performs each of these metric calculations to
determine associated displacement values and impact energy. The
output signal PPS_MAS Left from the accelerometer 62 is low-pass
filtered using, for example, a hardware filter 200 (anti-alias
filter). The low-pass filter 200 passes a signal of a first
frequency band, e.g., frequencies from 0-800 Hz. The filtered
signal is converted to a digital signal using an analog-to-digital
converter 202 for further processing by the ECU 80'. The ECU 80'
then high-pass filters the signal using a high-pass filter 204 so
as to remove any sensor bias (DC drift). The high-passed signal is
then further high-pass filtered 206 to eliminate frequencies from
DC-400 Hz where 400 Hz is a calibratable number. The output of HPF
206 contains frequency values between 400-800 Hz. The HPF 206 also
eliminates signal characteristics the result from rough road
events. A second high-pass filter can be cascaded to form a second
order filter to obtain a sharper cutoff if so desired. An absolute
value 210 of the high-pass filtered 206 signal is then determined
using function 210. The absolute value of the filter acceleration
signal is indicative of the impact energy based on the acceleration
signal from the left acceleration sensor 62. A moving average A_MA
of the absolute value of the signal is determined in function 211
for smoothing purposes. The resultant signal is a high-pass filter
signal 220, designated HPF_Left, and is indicative of impact energy
within a particular frequency range (e.g., 400-800 Hz) of interest.
This HPF_Left impact energy value is useful in determining the
occurrence of a vehicle/pedestrian impact event.
The output of the filter 204 is also used to determine displacement
values (double integral of acceleration) over a time window.
Specifically, the output of the HPF 204 is low-passed filtered by a
low-pass filter 208 so as to pass signals with a frequency between
DC and 220 Hz, for example. The output of the LPF 208 is processed
by a first moving average calculation function 230 (first integral)
followed by a second moving average calculation function 232
(second integral) to arrive at a first displacement value 234 which
is designated A_MA_Left.
Values for HPF_Right (impact energy right side) and A_MA_Right
(displacement value right side) are similarly determined.
The pressure left value from hose 160 as detected by the pressure
sensor 76' is low-passed filtered, using, for example, a hardware
filter 250, converted to a digital value using A/D converter 252
and high-passed filtered, by for example, a software high-pass
filter 254. A pressure moving average value is determined using
function 256 that provides the P_MA_Left moving average value 258
for further processing by the ECU 80'.
The P-MA-Right value is similarly determined.
FIG. 10 shows another sensor architecture, in accordance with yet
another example embodiment of the present invention, having the
acceleration sensors 62, 64 mounted to the cross-member 68 as
previously described. The pressure sensor 70'' includes a
multi-channel pressure ("PPS_MCP") sensor 76'' having four pressure
hoses connected thereto. The pressure sensor 76'' is a four channel
pressure sensor. A pressure hose 280 is mounted to the far left
portion of the bumper structure, a pressure hose 282 is mounted to
the left center portion of the bumper structure, a pressure hose
284 is mounted to the right center of the bumper structure, and a
pressure hose 286 is mounted to the far right portion of the bumper
structure. With this arrangement, the left and right sides of the
bumper each have two pressure signals that are used by the ECU 80''
for a vehicle/pedestrian impact analysis in a manner similar to
described above. With this structure, the pressure signals detected
from the two left pressure hoses could be either AND'ed or OR'ed to
provide a left side pressure safing determination. Similarly, the
pressure signals detected from the two right pressure hoses could
be either AND'ed or OR'ed to provide a right side pressure safing
determination. The resultant pressure safing determinations could
be AND'ed with the associated side discrimination determinations
based on the associated acceleration signal evaluations.
It should be appreciated that the present invention improves
vehicle/pedestrian impact sensing performance by providing a fast
time to deploy with a good margin against misuse and rough-road
conditions. The acceleration sensors, which serve as the primary
vehicle/pedestrian impact discrimination sensors, provide sensing
capabilities (e.g., frequency and amplitude) in discriminating
different types of impact events, while the pressure sensor(s)
provide a secondary vehicle/pedestrian impact discrimination sensor
that improves the system robustness by effectively providing a
filter against other types of non-impact vehicle events such as
experienced during rough-road conditions.
From the above description of the invention, those skilled in the
art will perceive improvements, changes and modifications. Such
improvements, changes and modifications within the skill of the art
are intended to be covered by the appended claims.
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